Women's Health

Experts Discuss Pros and Cons of Fish during Pregnancy

Women who are pregnant should include fish in their diet for optimal maternal health and fetal growth and development. That much health experts agree on.

But just how much fish moms-to-be can safely consume without exposing their unborn babies to dangerous levels of mercury is a matter of ongoing debate.

The US Food and Drug Administration (FDA) advises women to eat no more than 12 ounces a week, but a coalition of scientists in nutrition and medicine insists that expectant moms need at least that much or more.

"Recent data shows us that women are still not eating enough fish, and that's really alarming," says Judy Meehan, executive director of the National Healthy Mothers, Healthy Babies Coalition, an organization dedicated to disseminating the latest science on maternal and child health.

"There's simply no other way to get the omega-3s for brain development that you can from fish," she says.

High Omega-3, Low Mercury is Best

Fish is packed with omega-3 fatty acids, a beneficial type of fat that is considered important for neural development.

Limiting fish intake to the government-recommended level, in fact, could be "detrimental" to a child's mental development, British and American researchers reported in 2007 in The Lancet.

Their study found that children whose mothers ate at least three servings of fish a week during pregnancy performed better on tests of mental function.

In another study, Dr. Emily Oken, at Harvard Medical School, examined the balance between the nutritional benefit and contaminant risk of consuming fish during pregnancy.

She and her colleagues asked 341 women about their fish consumption during the second trimester of pregnancy and tested their blood levels for mercury.

When their children were three, they took a battery of tests to assess intelligence and motor skills.

"Test scores were highest in children of mothers who ate more than two weekly fish servings but had lower mercury levels, suggesting that the greatest benefit occurred when women ate fish low in mercury," says Dr. Oken.

"Even mothers who ate canned tuna more than twice weekly had children who scored better on tests, compared with those who did not eat canned tuna during pregnancy," she adds.

Another study looked at over 25,000 children born to Danish mothers. Kids whose moms ate more fish during pregnancy had better motor and cognitive test scores than those whose moms ate the least amount.

"Compared with women who ate the least fish during pregnancy, women who at the most fish - about 14 ounces per week, on average - had about a 30 percent likelihood of better development, about the same advantage a child would get from being one month older or from breast-feeding for more than one year," explains Dr. Oken.

Two Servings Per Week

In 2007, the National Healthy Mothers, Healthy Babies Coalition partnered with the Maternal Nutrition Group, an independent group of physicians, researchers and nutritionists, to encourage pregnant women to eat fish as part of a healthy diet. The concern was that many women were interpreting the FDA guidelines as a warning and curtailing their fish intake.

The FDA advisory, first issued in 2004, targets women who are pregnant or may become pregnant as well as nursing mothers and young children.

These populations are urged to avoid certain types of fish that may be higher in mercury and therefore toxic to a baby's or child's developing nervous system. These include shark, swordfish, king mackerel, and tilefish.

The FDA recommends choosing varieties lower in mercury and eating no more than 12 ounces - or roughly two meals - of fish a week. The total amount should include no more than 6 ounces of albacore tuna a week.

The American College of Obstetricians and Gynecologists echoes that advice in its own nutritional guidance.

Still, many Americans, including expectant moms, do not get at least two servings a week.

"The message is, eliminating fish is not a good thing," says Meehan. "Fish is uniquely important for brain development in babies."

Always consult your physician for more information.

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July 2009

Planning for Pregnancy

If you are planning to become pregnant, taking certain steps can help reduce risks to both you and your baby. Proper health before deciding to become pregnant is almost as important as maintaining a healthy body during pregnancy.

The first few weeks of pregnancy are crucial for a child's development. However, many women do not realize they are pregnant until several weeks after conception. Planning ahead and taking care of yourself before becoming pregnant is the best thing you can do for you and your baby.

One of the most important steps in helping you prepare for a healthy pregnancy is a pre-pregnancy examination (often called preconceptual care) performed by your physician before you become pregnant.

Other healthy steps:

smoking cessation

If you are a smoker, stop smoking now. Studies have shown that babies born to mothers who smoke tend to be lower in birth weight. In addition, exposure to secondhand smoke may adversely affect the fetus.

proper diet

Eating a balanced diet before and during pregnancy is not only good for the mother's overall health, but essential for nourishing the fetus.

proper weight and exercise

It is important to exercise regularly and maintain a proper weight before and during pregnancy. Women who are overweight may experience medical problems such as high blood pressure and diabetes. Women who are underweight may have babies with low birth weight.

medical management (of preexisting conditions)

Take control of any current or preexisting medical problems, such as diabetes or high blood pressure.

preventing birth defects

Take 400 micrograms (0.4 mg) of folic acid each day, a nutrient found in some green, leafy vegetables, nuts, beans, citrus fruits, fortified breakfast cereals, and some vitamin supplements. Folic acid can help reduce the risk of birth defects of the brain and spinal cord (also called neural tube defects).

Avoid exposure to alcohol and drugs during pregnancy. In addition, be sure to inform your physician of any medications (prescription and over-the-counter) you are currently taking - all may have adverse effects on the developing fetus.

exposure to harmful substances

Pregnant women should avoid exposure to toxic and chemical substances (i.e., lead and pesticides), and radiation (i.e., x-rays). Exposure to high levels of some types of radiation and some chemical and toxic substances may adversely affect the developing fetus.

infection control

Pregnant women should avoid the ingestion of undercooked meat and raw eggs. In addition, pregnant women should avoid all contact and exposure to cat feces and cat litter, which may contain a parasite toxoplasma gondii that causes toxoplasmosis. Other sources of infection include insects (i.e., flies) that have been in contact with cat feces and should be avoided during pregnancy.

daily vitamins

Begin taking a prenatal vitamin daily, prescribed by your physician, to make certain that your body gets all the necessary nutrients and vitamins needed to nourish a healthy baby.

identifying domestic violence

Women who are abused before pregnancy may be at risk for increased abuse during pregnancy. Your physician can help you find community, social, and legal resources to help you deal with domestic violence.